On August 25, Hurricane Harvey, the nation’s first major hurricane since 2005, made landfall in Rockport, Texas as a Category 4 hurricane. The storm hovered over Southeast Texas and Louisiana for days causing widespread flooding. Experts estimate storm damage around $70 billion with at least 70 lives lost. Hurricane Harvey was soon followed by Hurricane Irma, the most intense Atlantic hurricane in over a decade. Irma made landfall on September 6 in Barbuda as a Category 5 hurricane and continued through the Caribbean leaving at least 36 dead with damage ranging from major to total devastation. Irma made landfall in the Florida Keys on September 10 as a Category 4 hurricane eventually moving north up the state. Irma was responsible for 11 deaths and left over 6 million people without power. Hurricane Katia followed next leaving 2 dead in Mexico. The number and strength of these recent hurricanes have people talking about what impact climate change has had on this type of weather.
Many scientists believe that extreme weather events like hurricanes are more likely to happen and worsen because of certain conditions in place as a result of climate change. For example, hurricanes are pushing more water onto the shore because of the rising sea levels caused by climate change. Climate change has also resulted in a warmer planet creating more moisture in the air leading to more rain. The warmer air also means an eight meter per second increase in winds for every Celsius degree increase. An increase in winds means a stronger storm. The sea temperature in the area where Harvey formed was also warmer at both the surface and deep levels, having risen .5C over the past few decades. In addition, climate change has expanded the subtropical high pressure system explaining why Hurricane Harvey moved very slowly and stalled in areas because winds didn’t steer it off to sea as they usually do. The warming of the arctic may also contribute to this stalling behavior. High sea levels, warm air and water, and an expanded subtropical high pressure system are all things that hurricanes love.
“Attribution science” and climate models make it possible to explain how climate change is influencing hurricanes. However, scientists stop short of saying that climate change made a particular storm form the way that it did. Attributing climate change to specific events like Hurricane Harvey is difficult because computer climate models are only good at predicting large-scale weather patterns not localized events like tornados and hurricanes. In addition, these kinds of weather events have always happened and in some cases have been worse than what we are seeing today.
Would Hurricane Harvey and Irma have been different without the effects of climate change? Do you think that scientists will one day be able to credit climate change for causing specific hurricanes?